OrderProcessingSystem

A simple order processing example built with ASP.NET Core (API) and a background worker service that processes order-placed messages from RabbitMQ. The repo contains:

• OrderProcessingSystem.Api — REST API (Products, Cart, Orders, Authentication).
• OrderProcessingSystem.OrderPlacedService — background consumer (reads messages from RabbitMQ and sends email/log).
• docker-compose.yml to run everything (API, consumer, SQL Server, RabbitMQ, Seq).

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Table of contents

• Quick start (Docker)
• Prerequisites
• Ports & services
• Environment / configuration
• Run locally (dev)
• API overview (endpoints)
• Background worker
• Database & migrations
• Notes & TODOs
• Contact / next steps

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Quick start (Docker)

1. From repository root run:

docker compose up --build

This will build and start the API service, the background consumer, RabbitMQ, SQL Server and Seq as defined in docker-compose.yml.

2. Open API swagger (when container healthy):
   • API is exposed inside containers on ports 8080/8081 and mapped to host ports 5001/5002 in docker-compose.yml. Check http://localhost:5001/swagger (or https://localhost:5002/swagger) depending on your environment.

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Prerequisites

• Docker & Docker Compose (Docker Desktop or Docker Engine with Compose V2).
• (Optional) .NET 8 SDK if you want to run projects locally without containers.

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Ports & services (defaults from docker-compose)

• API: host 5001 -> container 8080 (and 5002 -> 8081).
• Consumer worker: host 6001/6002 mapped to worker ports.
• SQL Server: 1433 (container uses mcr.microsoft.com/mssql/server:2022-latest).
• RabbitMQ management: 15672, broker port: 5672.
• Seq (logging UI): 9090.

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Environment / configuration

Configuration lives in each project appsettings.json and is also injected via docker-compose.yml environment variables.

Important example settings:

• Connection string (SQL Server) — set in API appsettings.json and overridden from docker-compose: ConnectionStrings__DefaultConnection.
• JWT signing key (API): set in OrderProcessingSystem.Api/appsettings.json under Jwt:Key.
• RabbitMQ config: RabbitMQ:Host, RabbitMQ:User, RabbitMQ:Pass (used by API and worker). Defaults point to the rabbitmq service in docker-compose.yml.
• Email sender (consumer): OrderProcessingSystem.OrderPlacedService/appsettings.json contains EmailSender credentials used by the worker to send notification emails. Replace with secure values.

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Run locally (without Docker)

1. Ensure you have a SQL Server instance and RabbitMQ accessible.
2. Update OrderProcessingSystem.Api/appsettings.json connection string and RabbitMQ settings to point to your services.
3. From OrderProcessingSystem.Api run:

dotnet restore
dotnet build
dotnet run

4. For the worker service, run OrderProcessingSystem.OrderPlacedService similarly. The worker subscribes to order_exchange / order_queue and processes messages.

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API overview (main endpoints)

Swagger is configured in Program.cs and exposes the routes. Authentication is JWT-based.

Auth

• POST /api/Account/Register — register a user (body: RegisterUserRequestDto).
• POST /api/Account/Login — login and receive JWT (body: LoginUserRequestDto).

Products (public / admin)

• GET /api/Products — list products.
• GET /api/Products/{id} — get product by id.
• POST /api/Products — (Admin) create product.
• PUT /api/Products/{id} — (Admin) update product.
• DELETE /api/Products/{id} — (Admin) delete product.

Cart (user / admin)

• GET /api/User/cart — get authenticated user's cart items.
• POST /api/User/cart — add item to authenticated user's cart.

Orders

• POST /api/User/order — place order (uses user's cart items; sends message to RabbitMQ).
• Admin endpoints (in OrdersController) provide the ability to CRUD orders.

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Background worker / Message flow

• When an order is placed, the API constructs and sends an OrderPlacedMessage to RabbitMQ. The worker (OrderProcessingSystem.OrderPlacedService) consumes messages from order_queue, acknowledges them and sends an email (via IEmailSender) or logs the result.

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Database & Migrations

• EF Core migrations are present under OrderProcessingSystem.Api/Migrations. The initial migration creates Users, Products, Orders, OrderItems, CartItems tables with the indexes used by the app (unique cart item per user/product, unique order item per order/product).

If running locally, you can apply migrations with:

cd OrderProcessingSystem.Api
dotnet ef database update

(Ensure dotnet-ef is installed and appsettings.json connection string points to your DB.)

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Notes & TODOs (from code)

• The PlaceOrder flow has comments indicating planned improvements: stock quantity checks, transactional behavior, batch add/remove of order items, decrementing product stock when order placed.
• Secrets (SQL SA password, JWT key, email creds) are currently in docker-compose.yml and appsettings.json. Do not keep these in a public repo — move them to secrets or environment variables for production.

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Example curl flows

Register:

curl -X POST http://localhost:5001/api/Account/Register  -H "Content-Type: application/json"  -d '{"FirstName":"John","LastName":"Doe","UserName":"johnd","Email":"john@example.com","Password":"P@ssw0rd","ConfirmPassword":"P@ssw0rd"}'

Login:

curl -X POST http://localhost:5001/api/Account/Login  -H "Content-Type: application/json"  -d '{"Email":"john@example.com","Password":"P@ssw0rd"}'

Use the returned JWT in Authorization: Bearer <token> for protected endpoints (cart, place order, admin endpoints).

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Where to look in the repo (important files)

• docker-compose.yml — full service composition & envs.
• OrderProcessingSystem.Api/Program.cs — app startup, JWT, DI, Swagger.
• OrderProcessingSystem.Api/Controllers/* — controllers for Accounts, Products, Orders, Cart, User.
• OrderProcessingSystem.OrderPlacedService/Worker.cs — RabbitMQ consumer logic.
• OrderProcessingSystem.Api/Migrations/* — EF Core migrations.

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Next steps / Help I can provide

• Add a Development section (run with Visual Studio / launch profiles).
• Implement the TODOs: transactional order placement and stock decrement.
• Add Postman collection or example requests.
• Sanitize secrets and add example .env and .env.example.